The present invention relates generally to a transducer and more particularly to an acoustical transducer for use as an ear insert receiver.
Magnetic transducers are well known for use as ear insert receivers. The most commonly used transducer is a moving armature type, often referred to as a controlled magnetic or variable reluctance transducer.
As well known, the variable reluctance transducer must be precision adjusted to center the movable armature between the pole pieces of the magnetic circuit. Thus, the variable reluctance transducer is particularly sensitive to any force offsetting the armature, such as shock, vibration, mechanical stress on the transducer housing or extreme variations in temperature.
Other factors and structural features of the variable reluctance transducer further exaggerate this sensitivity problem. The armature is usually a soft ductile alloy with a very low yield strength. As such, the armature is easily deformed.
In many transducers, particularly receivers driven by a single-ended amplifier, a D.C. bias current is unavoidable. Such a bias current will offset the armature of the variable reluctance transducer with respect to the pole pieces and thereby adversely effect operation and efficiency.